Rotary piston mechanism



E. POMAR ROTARY PISTON MECHANISM June 4, 1963 3 Sheets-Sheet 1 Filed Jan. 31, 1962 mmz I. M

June 4, 1963 E, POMAR 3,092,031

ROTARY PISTON MECHANISM Filed Jan. 51, 1962 3 Sheets-Sheet 2 ZAodara uma:-

June 4, 1963 E. POMAR 3, 3

ROTARY PISTON MECHANISM Filed Jan. 31, 1962 3 Sheets-Sheet 3 w C I-- 724 4 3 a. (ma, Mr?

3,092,031 ROTARY PISTGN MEQHANISM Eliodoro Pomar, 41 Via Sanvito Siivestro, Varese, Italy Filed Jan. 31, 1962, Ser. No. 170,126 Claims priority, application ltaly .Ian. 31, 1961 6 Claims. (Cl. 103-129) This invention generally relates to rotary piston mechanisms which may be used as prime movers and, more particularly, as internal combustion engines or motors, and as pumps, compressors, driving and/or driven hydraulic transmission means or the like.

More particularly, the present invention is concerned with the kind of rotary piston mechanisms in which the piston means consist in a series of vanes mounted for rotation in a chamber of generally cylindrical shape, the vanes being adapted to be moved relatively to one another during their rotational movement to form series of pockets of progressively increasing and decreasing cross-section.

It is known to those skilled in the art to which this invention appertains that a great number of rotary piston mechanisms of the kind referred to above had been heretofore proposed. While several prior mechanisms have been satisfyingly proved as made use of as pumps or compressor and like driven rotary devices wherein a source of rotary power is applied to the device drive shaft for supplying pressurized liquid or preferably gaseous media, the use of such mechanism as prime movers, namely as internal combustion engines, did not lead practical results.

In general, the most serious problem faced in the provision of prime movers embodied in mechanisms of the above kind and not heretofore solved is involved in the correct and positive transformation of the tangential pressure exerted by an expanding gaseous medium on the said vanes, during the cycle of operation of the motor, into a rotary drive applied to the mechanism shaft. The various transmission means heretofore proposed for drivingly connect said vanes to said shaft revealed a substantial tendency to behave as a so called one-directional transmission, wherein the one direction admitted is from shaft to vanes. More particularly as the mechanism is made use of as an internal combustion engine, the pulsing-type action exerted on the vanes is of further prejudice of the proper transmission and transformation of the applied expansive power generated into the pockets.

It is therefore a primary object of this invention to provide a new and advantageous rotary piston mechanism which is not subject to the objection common to prior mechanisms of the kind above described and which may be advantageously made use of as and embodied in a prime moverin particular in an internal combustion engine-wherein the power is applied as a pressure of an expanding gaseous medium in the said pockets and exerted on the adjacent vanes for transferring andtransforming said power as a source of rotary continuous motion of the engine shaft.

Another object of this invention is to provide a new and improved rotary piston mechanism of the above kind, wherein the cycle according to which the positive and negative incremental ratio of the rotational move ments of the vanes relatively to one another, during the Patented June 4., 1963 ice 2 cycle of operation of the device, may be differing in one phase in respect with other phases of such cycle-whereby the variations of volumes of said progressively increasing and decreasing pockets may be made best adapted for performing the various compression, expansion and exhaustion phases of the cycle.

According to an important aspect of this invention, the mechanism of the invention includes a plurality of vanelike pistons mounted for rotation about the axis of the cylindrical chamber, the number of said vanes being odd and preferably three. Each piston is pivotally linked to a second pivotal connection of an endless chain-like linking means including a number of links which is twice the said odd number of piston, and wherein any first pivotal connection between adjacent links, located between the pivotal connections linked to the pistons, is guidedly caused to follow a not circular path, while obviously anyone of said second pivotal connection, linked to a piston, is caused to follow a circular path having its center on said axis. The drive shaft :of the mechanism is rotatably connected to at least one of the said firstpivotal connection, by means of a slide crank type connection, for example.

As the above essential conditions are satisfied, and upon proper definition of the said not circular path, a proper cycle of rotational movement of the vane-like pistons relatively to one another may be provided; The said not circular path may be defined by camming surfaces adapted to be followed by cam follower means secured to the said first pivotal connections. The said camming surfaces may define a not circular path which may be symmetrical with respect to a diameter of said circular path, be elliptical for example, or which may be not symmetricalwhereby diifering increments and decreasing of the rotational relative speed of the pistons may be produced in the complete cycle of operation, thus attaining the above said another object of this invention, if desired.

Further objects and advantages of the invention reside in the arrangement of parts and in the details of construction of the various essential components of the mechanism, in their combination and in the mode of operation of the rotary mechanism as Will be hereinafter described.

In accomplishing the above mentioned and other objects of the invention, and in making use of and enjoying the various phenomena involved therewith, there are provided the improved features and details of construction of the essential components of the mechanism, one preferred form of embodiment of which is illustrated in the accompanying drawings, forming an essential component of this disclosure, and wherein:

FIGURE 1 is a vertical longitudinal sectional view through the mechanism of the invention, along the line 1-1 of FIGURE 2, which in turn is a cross-sectional view of same, taken along the line 2-2 of FIG. 1;

FIGURES 3, 4 and 5 are further cross-sectional views of same, taken along the lines 3-3, 4-4 and 5-5, respectively, of FIG. 1, showing the rotational connection to the mechanism drive shaft, and respectively the endless chain type linking means and the guide means pro vided for causing a part of the components of such linking means to follow a not circular path;

FIGURES 6, 7 and 8 diagrammatically illustrate three forms of embodiment of cammiug surfaces which may be alternatively included in said guide means to provide differing not circular paths; and

FIGURE 9 is a graph illustrating the differing eifects attained by making use of any of said diifering camming surfaces.

Referring first to FIGS. 1 and 2, wherein the mechanism of this invention is embodied in a rotary motor, namely an internal combustion engine, shown in a somewhat simplified manner:

In the form of embodiment shown, the motor includes a stationary casing 24- of generally cylindrical shape, wherein a cylindrical chamber 10 is formed, having its axis at -0. According to an important aspect of the invention, the mechanism is combined with a motor having an odd number of vane-like pistons, such as three vanes or pistons 11, 12 and 1-3, mounted for rotation inside said chamber about the said axis 0-0 thereof, and defining variable volume spaces therebetween, such as spaces 36, 37 and 38 of FIG. 2. The positive and negative variations of volume of said spaces, according to the cycle of operation of the motor, are made use of for causing a conventional cycle of operation of an internal combustion engine, either spark plug ignited or injection ignited, according to current art.

The said' stationary casing 24 is therefore provided with suitably arranged two inlet and outlet passages 18 and 19, respectively, and with suitably threaded means 26 adapted for suitably locating an igniting and/or fuel feeding means, such as a spark plug or a diesel-type injector. The various ancillary devices of the motor, such as the several carburetting, feeding, igniting, exhausting and lubricating means, have been omitted in the drawing and will not be further described, as appertaining to current knowledge of the art and as not being claimed matter of this invention, as defined in any by the appended claims. The motor includes further a main motor shaft 14, supported for rotation inside said chamber 10' for rotation about said axis 0-0, by means of ball-bearing means 21 and 22, supported in and by symmetrically and oppositely located cover members 23 of the said casing 24, for example.

The linking means drivingly connecting the said vanes 11, 12 and 13 to the said shaft 14 are adapted, according to the invention, either for having the said vanes or at least a part thereof driven by the said shaft, such as during the compression phase of the cycle of operation of the internal combustion engine, and for having the said shaft driven by said vanes, such in the expansion phase of said cycle. For proper balance of the transmitted power, such means, which will be described in detail hereinbelow, are preferably symmetrically constructed and located at both oppositely located portions 25 and 26 of the assembly. The following disclosure, mainly related to the means located in the portion 26 only, for simplicity sake, is therefore also intended as referred to the symmetrical components and members located and operating in the other portion 25.

According to another important feature of the invention, the said linking means include an endless chain forming assembly of connecting links, alternatively indicated at 30 and 31 in FIGS. 3 and 4, the number of the links and therefore of the link pivots included in said assembly being twice the number of said vanes, namely being six. Any second link pivot in said endless chain linking means is connected to one vane 11, 12 and 13, preferably by means of longitudinal rods 27 and respectively 28 and 29, constructed and arranged as shown in FIGS. 1, 2, 3 and 4, for example. The end portions of such rods 27, 28 and 29 embody the pivots of the said second link pivots and define the pivotal axis thereof.

Assumed that the said second link pivots such as indicated at 27, 28 and 29 in FIGS. 3 and 4 (as being embodied by the end portions of the correspondingly referred 1. rods) are each connected to one vane 11 or respectively 12 and 13, such second link pivots and the axis thereof are caused to travel along a circular path having its center on the axis of main shaft.

On the contrary, each first link pivot such as indicated at 32 in FIGS. 1, 3, 4 and 5, each located between two of said second link pivots, is guided to follow a not circular path by suitable guide means, such as a cam member 34 having a camming surface 33 thereinto, and along which proper cam follower means, such as ball bearings 36 (FiGS. 4 and 5) are slidably and preferably rollingly engaged, as shown in FIGS. 1 and 5, for example, each ball bearing 35 being mounted for idle rotation about one pivot 32.

The said canuning surface 33 is dimensioned and shaped, in relation with the radius of the said circular path of second pivots at 27, 28 and 29 and with the interpivotal length of each connecting link 30, 31, so that each cam follower means, such as said ball bearings 35, contacts anytime the camming surface. Owing to the not circular path of said first link pivots at 32, the polygon embodied by said link assembly 30, 31, as having a part of its vertexes anytime on the said circular path and the remaining part of its vertexes anytime on said not circular path, is therefore caused to cyclically modify its shape, and the spacings between adjacent second link pivots at 27, 2S and 29 are at their turn therefore caused to cyclically vary. Such variation of shape and of spacing between seoond link pivots of the polygonal chain link means 30, 31 causes the desired motion of said vanes 11, 12 and 13, relatively to one another during their rotational movement, and the desired consequent cyclical increasing and decreasing of the cross-section of pockets or spaces 36, 37 and 38 therebetween, ie, the desired variation of volumes of said spaces.

The drive connection between the said polygonal link assembly 30, 31 and the shaft 14 may be embodied by a proper rotational connection having a link at, at least one of, said first link pivots 32, such as a brace 39 (FIGS. 1 and 3), having proper counter-balancing masses 40 secured to or integrally formed therewith, and slidably engaging with a slide member such as at 41 pivotally connected to one pivot 32, for example.

Upon consideration of what above and of the accompanying drawings, two important results of the invention may be readily understood, as summarized below:

Assumed that the number of vanes is odd, the pressures existing in any space 36, 37 and 39, during the compression and expansion phases of the cycle of operation of the motor, are obviously equally and balancedly ap plied to both adjacent vanes 11 and 12, or 12 and 13, or 12 and 11, respectively. Such adjacent vanes, however, are never connected to the shaft 14 by link means which may be simultaneously positioned in an equal or symmetrical condition or position relatively to one another, owing to the oddness of the number of vanes.

According to the invention, it has been found that such feature is essential and critical to prevent the mechanism to be hampered when the direction of drive is inverted. Further, in the operation of the described mechanism, the law which defines the variations of rotational movement of the vanes, relatively to one another, is obviously determined by the shape of the said not circular path of the first link pivots at 32, namely of the said camming surface at 33. Now, provided that the condition of constant engagement of the cam followers with the camming surface would be satisfied, an ample latitude of selection may be enjoyed in providing such camming surfaces shaping. The new and advantageous results of such important feature of the invention might be readily understood from a consideration of diagrammatical FIGS. 6, 7, and 8, when compared with the curves of the graph of FIG. 9, wherein such curves indicate the variation of volume W of any space such as 36, 37 or 38 during a full rotation of any vane such as 11, 12 and 13 from 0 to 360 (0:360").

Differing not circular paths 33a, 33b and 330 are shown in FIGS. 6, 7 and 8, respectively, as provided by corresponthngly shaped camming surfaces. The camming surface 33 of FIGS. 3, 4 and 5 is shaped to define a not circular path of the character indicated at 33c in FIG. 8, for example.

Assuming that a camming surface adapted to provide a not circular path such as at 33a is made use of in the mechanism of the invention, there is shown that said path is symmetrical with respect with two axis x--x and yy, crossing at right angle on rotational axis of the vanes, i.e. in the center of the circular path of the second link pivots. A typical example of such path shape is given by an ellipse. In such case the variation of volume W follows a substantially sinusoidal law, as graphically shown by curve Wa of FIG. 9, and having its peaks and pits at same upper and respectively lower values and evenly spaced at 90 and 270 and respectively at 0=360 and 180 along the abscissa. From the point of view of the operation of an internal combustion engine, such law correspond to the law of volumetrical variation of a conventional piston engine having reciprocating pistons.

By causing the said first link pivots at 32 to follow a path such as shown at 33b in FIG. 7, Whose shape is symmetrical with respect to one axis yy only, the volume W variation follows the law such as defined by curve Wb in graph. By making use of camming surfaces of the type defined by typically oval shape 33b, therefore, it is possible, for example, to cyclically have smaller minimum volumes followed by greater minimum volumes, owing to the greater level of pit at 180 than at 0=360. Such feature may be usefully enjoyed for having a proper compression ratio of the motor, and a quite full exhaustion of burnt gases, for example. In such case the 90 spacing of peaks and pits of the curve is constant, as in the case of curve Wa.

Further, by providing guide means such to define a not circular path of the type shown at 330 in FIG. 8, a most interesting curve of variation may be attained, such as shown at We in the graph. Such slant oval path causes not only the volume W to drop at differing minimum values at 180 and at 0=360, respectively, thus attaining the above analyzed advantageous results of the shape 33b of FIG. 7, but also causes a marked variation of the spacings between peaks and pits of the curve, and more particularly of the pendency of the curve. For example, curve Wc steps down from its peak at 110 about at a negative angle whose value is far greater than the value the positive angle of raising of the curve from its pit at 0=360 to the said peak at 110.

It is well recognized by those skilled in the art of internal combustion engines that it will be greatly desirable to have an expansion phase smoother and longer than the pure amplitude of 90, and that such desirable feature is however proved as not practically obtainable by applying current knowledge of the art.

It is to be evident that the present invention includes various advantageous features, and it Will be understood too that each of the new features described and any com bination thereof may also find useful application in other types of construction and mechanism differing from the one described.

While the invention has been heretofore described and shown but in one form of embodiment thereof, it is intended that the invention is not limited to the very details shown, and that said details should not be taken as restrictive of the invention, as it is obvious that various modifications in design may be resorted to by those skilled in the art to which this invention appertains, without departing from the spirit and the scope of the invention, as defined in and by the appended claims.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various applications in rotary mechanisms of the type considered, without omitting features that, from the standpoint of prior art, fairly constitute characteristic of the invention and, therefore, such adaptations should and are intended to be comprehended within the range of equivalents thereof.

Having thus described the invention, what is claimed as new and desired to have protected by Letters Patent is:

1. A rotary piston mechanism comprising a casing, a chamber of circular cross-sectional shape inside said casing and defining an axis, a plurality of piston forming vanes which are independently rotatable in said chamber about said axis to form a corresponding plurality of variable volume spaces therebetween in said casing, the number of said vanes in said plurality being odd, endless chaintype link means located outside said chamber about said axis including a plurality of link members chain-likely interconnected by a corresponding plurality of chain-like link pivots, the numbers of said link members and of said link pivots being twice the number of said vanes, the said link pivots including second pivots and first pivots alternatively located along said endless chain-type link means, means to connect each vane to one single second pivot for drivingly connecting said vanes to said link means at said second link pivots and to cause said second link pivots to follow a circular path having its center in said axis upon rotation of said vanes in said chamber, and guide means engaging each first link pivot to cause said first pivots to follow a not circular path about said axis as said second pivots follow said circular path, whereby the said vanes are caused to move relatively to one another during their rotational movement about said axis in said chamber to cyclically vary the volumes of said spaces, upon the cyclical variation of spacing between adjacent second link pivots along said circular path as the respectively intermediate first pivot follows the said not circular path.

2. In a rotary piston mechanism as defined in claim 1, the not circular path defining guide means consisting of cam means defining a camming surface of not circular shape about said axis, and of cam follower means connected to each said first link pivot and in constantly engaged relationship with said camming surface.

3. In a rotary piston mechanism as defined in claim 1, the not circular path defining guide means shaped to define a typically elliptical not circular path symmetrical with respect with two symmetry axes perpendicularly inter-crossing in said chamber axis, whereby causing the said vanes to move relatively to one another during their rotational movement about said axis for cyclically varying the volumes of said spaces formed therebetween in said chamber according to a variation law as defined by a curve of volumes as a function of rotary motion, including evenly spaced peaks and pits, wherein the said peaks and pits are at the same upper and respectively the same lower level during a whole 360 cycle of rotation of any vane.

4. In a rotary piston mechanism as defined in claim 1, the not circular path defining guide means shaped to define a typically oval not circular path symmetrical with respect to one symmetry axis inter-crossing the said chamber axis, whereby causing the said vanes to move relatively to one another during their rotational movement about said axis for cyclically varying the volume of said spaces formed therebetween in said chamber, according to a variation law as defined by a curve of volumes as a function of rotary motion of any vane, including peaks and pits, wherein pits at dilfering curve levels are included in the curve defining a whole 360 cycle of rotation of any vane.

5. In a rotary piston mechanism as defined in claim 1, the not circular path defining guide 'means shaped to define a typically slanting annulus shaped not circular path not possessing symmetry conditions with respect to any line in the plane of said path and crossing the said chamber axis, whereby causing the said vanes to move relatively to one another during their rotational movement about said axis for cyclically varying the volume of said spaces formed therebetween in said chamber, according to a variation law as defined by a curve of volumes as a function of rotary motion of any vane, including slanting portions between peaks and pits thereof and representing the variational ratio of the positive and negative variations of said volumes, the absolute values of mean inclination of said curve portions being different Where representing a positive and, respectively, a negative volume variation during a whole 360 cycle of rotation of any vane. p

'6. A rotary piston mechanism as claimed in claim 1, including three piston forming vanes in said chamber and endless chain type link means including six link members, three first pivots and three second pivots alternatively located along said link means.

References Cited in the file of this patent UNITED STATES PATENTS 1,330,629 Gooding Feb. 10, 1920 1,904,892 Trube Apr. 18, 1933 10 2,147,290 Gardner Feb. 14, 1939 FOREIGN PATENTS 267,565 Great Britain Sept. 22, 1927 

1. A ROTARY PISTON MECHANISM COMPRISING A CASING, A CHAMBER OF CIRCULAR CROSS-SECTIONAL SHAPE INSIDE SAID CASING AND DEFINING AN AXIS, A PLURALITY OF PISTON FORMING VANES WHICH ARE INDEPENDENTLY ROTATABLE IN SAID CHAMBER ABOUT SAID AXIS TO FORM A CORRESPONDING PLURALITY OF VARIABLE VOLUME SPACES THEREBETWEEN IN SAID CASING, THE NUMBER OF SAID VANES IN SAID PLURALITY BEING ODD, ENDLESS CHAINTYPE LINK MEANS LOCATED OUTSIDE SAID CHAMBER ABOUT SAID AXIS INCLUDING A PLURALITY OF LINK MEMBERS CHAIN-LIKELY INTERCONNECTED BY A CORRESPONDING PLURALITY OF CHAIN-LIKE LINK PIVOTS, THE NUMBERS OF SAID LINK MEMBERS AND OF SAID LINK PIVOTS BEING TWICE THE NUMBER OF SAID VANES, THE SAID LINK PIVOTS INCLUDING SECOND PIVOTS AND FIRST PIVOTS ALTERNATIVELY LOCATED ALONG SAID ENDLESS CHAIN-TYPE LINK MEANS, MEANS TO CONNECT EACH VANE TO ONE SINGLE SECOND PIVOT FOR DRIVINGLY CONNECTING SAID VANES TO SAID LINK MEANS AT SAID SECOND LINK PIVOTS AND TO CAUSE SAID SECOND LINK PIVOTS TO FOLLOW A CIRCULAR PATH HAVING ITS CENTER IN SAID AXIS UPON ROTATION OF SAID VANES IN SAID CHAMBER, AND GUIDE MEANS ENGAGING EACH FIRST LINK PIVOT TO CAUSE SAID FIRST PIVOTS TO FOLLOW A NOT CIRCULAR PATH ABOUT SAID AXIS AS SAID SECOND PIVOTS FOLLOW SAAID CIRCULAR PATH, WHEREBY THE SAID VANES ARE CAUSED TO MOVED RELATIVELY TO ONE ANOTHER DURING THEIR ROTATIONAL MOVEMENT ABOUT SAID AXIS IN SAID CHAMBER TO CYCLICALLY VARY THE VOLUMES OF SAID SPACES, UPON THE CYCLICAL VARIATION OF SPACING BETWEEN ADJACENT SECOND LINK PIVOTS ALONG SAID CIRCULAR PATH AS THE RESPECTIVELY INTERMEDIATE FIRST PIVOT FOLLOWS THE SAID NOT CIRCULAR PATH. 